Until now in the field of sheet metal V-pulleys and sheet metal brake shoes, a manufacturing method such that a rotating splitting roller or a rotating cleaving roller is pressed against the outer peripheral part of a circular metal material to split such a part into two parts is known (refer to Patent literature 1).
Further, another manufacturing method of a pulley or a brake shoe has been disclosed (refer to Patent literatures 2 and 3). In such a method, the objects are manufactured by cleaving process using a cylindrical-shaped cleaving punch instead of the above-mentioned rotating splitting roller or rotating cleaving roller, or by cutting the circumferential peripheral part of a bottomed cylindrical metal body with a cutting die followed by a drawing process applying to the cut part with a press die.
The above-mentioned V-pulleys and brake shoes are made of a circular metal material. If there is a technique that is applicable to the longitudinal splitting of the end part of a metal plate having any of a rectangular, polygonal, or elliptical shape, or a metal rod having a cross-section of any of a circular, elliptical, rectangular, or polygonal shape, i.e., materials other than circular metal materials, various applications of such a technique will be promising. As a technology to respond to such needs, the inventors of the present invention have already developed a novel method for performing an end-splitting of a metal plate or a metal rod (refer to Patent literatures 4 and 5). The developed end-splitting method repeats press-splitting using a splitting punch or a cleaving punch consecutively many times, not only one time, and moves the position of a clamping die for pinching the metal plate or the metal rod at each time of the press-splitting operation to an optimized condition so that the length of the incision in the splitting can be freely adjusted within the range freely specified.
On the other hand however, metal containers are encountering a new demand although metal containers have been used in thermos bottles, vacuum isolation cooking utensils, or heat insulating containers. In recent years with the innovation of technologies in electrical and electronic devices and in transportation such as electric or fuel cell automobiles, low-cost metal containers of high-performance, high-reliability, high-durability, and high-productivity are strongly demanded as storing containers for battery electrolytic solution and as storage containers for such as gasoline, natural gas, or hydrogen. Further, there are similar needs for metal tubes (pipes) in heat-exchangers such as radiators, condensers, or oil-coolers.
As a method of manufacturing metal containers and metal pipes, it has been a conventional well known technique that predetermined components, after having been formed by press working or drawing work, are joined using welding (including laser welding) or brazing (refer to Patent literatures 6 and 7). Moreover, in some cases, a metal container of desired style is formed using another method such as hydraulic bulge forming after joining the bottom member of the container with the other end of the barrel member by welding or similar manner
{Patent Literature 1}                Japanese unexamined patent application publication No. SHO 61-129241        
{Patent Literature 2}                Japanese unexamined patent application publication No. HEI 8-300082        
{Patent Literature 3}                Japanese unexamined patent application publication No. 2002-45940        
{Patent Literature 4}                Japanese patent No. 5165806        
{Patent Literature 5}                Japanese patent No. 5219178        
{Patent Literature 6}                Japanese unexamined patent application publication No. 2012-94358        
{Patent Literature 7}                International publication No. WO 2003/052337        